Wireless telegraphy



June 9; "1925;

H. ABRAHAM WIRELESS TELEGRAPHY Filed sept. 2,- 1921 2 Sheng-sheet 1 wmv/'0H Arr fwn June '9, 1925e 1,541,608

v H. ABRAHAM WIRELESS TELEGRAPHY Filed Sept. 2,' 1921 2 sheets-sheet 2 lli lune 9, i925.

iNTED STATES PATENT @FEiG-E.,

v-IEIIRI ABRAHAM, 0F PARS,'FRA-TCE.

XVIRELESS TELEGRAPHY.

Application filed September 2, 1921. Serial No. 498,013.

To all whom t may con-cern.:

Zen ofthe Republic otFrance, and resident of Paris, France, post-@Hice address True Denfert-Rochereau, have invented new and useful. mprovements in YWireless "lelegraphy, which improvements are fully set forth in the followingv specication.

rIhe present invention relates to improve-v ments in wireless telegraphy. The object of the invention is an installation by means ot which, without the reduction Vof broadcasting area, two or a larger number or messages lmay be transmitted simultaneously from the same antennae, the transmitting station working yat full power for each of the simultaneous transmissions, and the trans mission of each message being effected on a group of waves of characteristic wavelengths.

Multiplex wireless telegraph systems have already been constructed, and in certainot these systems two groups of high-frequency waves are sent out at Athe Sametime, with a different frequency for each ol:V the two messages. Such system, however, involves the serious objectionthat the power must he divided between the two messages.

In the systems referred to, if only 100 kilowatts are available, the maximum that can be utilized for each message is kilowatts, which would greatly reduce the vetlective broadcasting area. Vl-Tith the present invention, on the contrary, the broadcasting station can be operated at full power for all ot the messages at the same time.

In other known systems, high-speed commutators are used which, even in the transmission ot a single massage, cause the groups ot' waves emitted by the antenna to be in-` terrupted many hundreds of times per second. rIhis presents the serious ditliculty that hallA ot the time is wasted, and the range of the broadcasting station is greatly decreased. The range is still further reduced because all of the power ot thestation cannot be utilized even in sending a single message. Finally, this system `is not applicable to large stations, because it is not yet known how to successfully employ high-powered rotary commutators giving sutliciently rapid coml mutations in high-frequency currents. Be it known that I, HENRI ABRAHAM, citi- The present invention involves none ofthese objections.

Moreover, this invention differs essentially from prior known systems which. permit the superposition of a wireless'telephone message and a wireless telegraphl message-hut which are incapable of sending two telegraph messages. My improved system is specially adapted for wireless telegraphy.

Let it first be supposed that only two wireless messages are to be sent simultaneously. The first message is transmitted at a certain wave-length L1, and the second message at another wave-length L2. The transmitting devices (keys) may act independently for the two emissions, but the apparatus is so arranged that during the moments when the 4manipulations (effecting the two emissions simultaneously coincide, the resultant emission'is madeat athird wavelength L3 quite distinct from the two characteristic wave-lengths L1, L2. Thus the first message is transmitted at one time on L1 and'at another time on L3; the second message is transmitted sometimes on L2 and sometimes on L3, ythe emissions being however, alwayseected at full power.

At the other end in the lirst receiving station, the arrangement `is such that reception is effected equally well at vwave-length L1 as at'wave-length L3. At-the same time. in the second receiving station, reception lakes place equally well at either one or the other ot the wave-lengths L2 yand L3.

yEach of. the receiving stations receives its message without interference by the olher transmission, and there is no reduction in broadcasting area as the emissions are always made at full power.

In the casevof three simultaneous transmissions, the separate wave emissions madeat three wave-lengths L1, L2` and L3, but the coincidence of two wave emissions results in three-further waves yot lengths L4, L5 and LG, respectively; while thecoincidence of all three Wave emissions Jfurnishes a seventh wave-length L7. Each receiving station is arranged to receive equally .well at its own characteristic Wave-length and at the three other wave-lengths resulting from the coincidence of the wave emissions. The various receiving stations may be installed at the saine locality and may have parts in common, such as antennae or receiving frames or even oscillating circuits controlled for certain resonnances.

Certain installations will hereinafter be described which may be used for sending and receiving but which, it should be well understood, are only given by way of example, in order to more clearly explain the invention.

The accompanying drawing shows by way of example diagrams of particular installations for the transmission and reception of two messages simultaneously.

In said drawing:

Figure 1 shows a transmitting station for two simultaneous transmissions from the same generating means.

Fig. 2 is a representation of an installation adapted to receive two diEerent wavelengths, receiving being effected by a single antenna.

Fig. 3 relates to a modication, in which reception takes place on two frames.

In Fig. 1, the antenna l and the self inductance 2 of the antenna are arranged in series with the source of transmitting current 3 and the ground connection 4:. Two auxiliary circuits 5 and 6 are excited by the circuit of the antenna, and the closing of the keys 7 or 8 causes a change in the length of the emitted waves. These auxiliary circuits may be provide-d with self-inductances or capacities and may be excited by direct or inductive coupling. The induction may be produced by the self-inductance of the an tenna itself or by a separate winding. The more simple hook-up is shown in the gurc. The self-inductance of the antenna 2 acts by induction on the circuits 5 and 6, and the coupling is so regulated as to obtain the desired changes of wave-lengths. The instruments represented by the keys 7 and 8 may be of any desired type, viz. single or multiple-break- Moreover, each of the circuits may be replaced by a group of relay circuits Vexcited and worked simultaneouslyY in such a manner that the keys 7 and 8 need only interrupt very weak currents. The manipulations may be effected by short circuiting a. self-inductance or a capacity forming part of an oscillating circuit, and may be effected by hand or automatically.

In the arrangement shown in Fig. 2, i. e., receiving stations for two wave-lengths, receiving is effected from a frame or an antenna 1" and a ground connection 2".

As shown in Fig. 2, the receiving station comprises two groups of multiple resonating circuits connected in series with the antenna l. The latter is connected by a self-inductance 2 and a variable condenser 3 with the first group of resonating circuits A, B and by a self-inductance 2 and a variable condenser 3" group of resonating circuits A', B; the ground connection 2" being made from the discharge side of the inductance 2.

It is considered unnecessary to show and describe each group of resonating circuits, as the two groups are alike. One groupwthat located at the upper part of Fig. 2, for example-comprises an amplifying device or audion containing a filament t, a grid 5" and a plate 6". The circuit of plate 6" contains a winding 7 which operates by reactance on the circuit 2, 3" and it also contains a winding 8' for coupling it by induction with a second resonating circuit. This latter is formed by the inductance 9" and the condenser 10, the terminals of which are also connected to the filament 11" and grid 12" of a second amplifying device or audion, the circuit of which contains a'reactance 14:". The plate batteries are represented at a and b, and the heating battery at c.

The other group of resonating circuits is identical with the first one, excepting that it is tuned for a different wave-length.

'Ihe two condensers 10" and 10" are connected to the filaments 15', 15" and to the grids 16', 16" of two other amplifying devices or audions. The plates of these two latter audions are fed, across one and the same resistance 22 or a single self inductance, by a battery d.

`There is 'need to remark that the audion 11, 12, 13 of one group and, similarly, the audion11"',12"',13" of the other group are utilized exclusively to produce reactance by the circuits 14", 14m; and that entirely different audions (15', 16', 20 in one group and 15, 16", 20" in the other group) are employed to respectively connect the oscillating circuit 9", 10 on the one hand, and 9', and 10"" on the other hand with the rest of the apparatus.

The receiving apparatus comprises amplifying device or audion 25, 26, The electro-magnet 28 of the receiving apparatus is arranged, as shown, between the the plate 27 of the device and the positive pole of the plate battery e which has been represented as separate from the battery Cl, but which could be combined with it. l

The grid 26 is connected at one side to the filament 25 by the resistance 29, and at the other side to the plates 20', 20" by the condenser 30, as usual in wireless installation.

The oscillating circuits A-B and A-B' having been tuned to resonate respectively for the two wave-lengths to be received at the station, it can be seen that they receive exclusively only on one or equally well on the other wave-length.

Fig. 3 shows, as already mentioned above,

with the secondv a practical embodiment of a receiving apparatus in which receiving is effected yby two frames 1,1. The same elements. are represented'in thisfigure as are shown in Fig. 3.

It should beclearly -understood that the installations hereinbefore described' -are given so-lely by way of examples, `Vand that the arrangements may bevaried as desired without departing from the spirit or scope of the invention.

I claim as my invention y '1. A system of radiotelegraphy, for simultaneously transmitting several messages in the same direction from a single sending station, each message at full power so as to avoid decreasing the se-nding area, compris' ing a series of independent manipulating devices at the sending station so arranged that by manipulating one of said devices emissions are produced at the wave-lengths characteristic of that device, and that when another device is manipulated the emissions have wave-lengths which are characteristic of the second device and different from those of the first device; and a series of receiving devices at the receiving station equal in number to the manipulating devices at the sending station, each receiving device being so arranged as to be capable of receiving equally well at a predetermined series of different wave-lengths which are the same as those sent out by the sending station when 'a certain manipulating device is operated.

2. A system of radiotelegraphy, for simultaneously transmitting several messages in the same direct-ion from a single sending station, each message at full power so as to avoid decreasing the sending area, comprising a series of independent manipulating devices at the sending station so arranged that by manipulating one of said devices emissions are produced at the wave-lengths characteristic of that device, and that when another device is manipulated the emissions have wave-lengths which are characteristic of the second device and different from those of the first device; and a` series of receiving devices at the receiving stat-ion equal in number to the manipulating devices at the sending station, each receiving device comprising resonating circuits connected with the grids of amplifying devices, the anodes of which are fed with electric current across one and the same translating device.

3. A system of radiotelegraphy, for transmitting a plurality of signals at full power at the same time and in the same direction, comprising a sending station adapted to send each group of signals at a wave-length characteristic for that group, and coinciding groups at resultant characteristic wavelengths distinct from any of the other characteristic wavelengths; and a receiving station adapted to receive each group of signals at the vcharacteristic wave-length of that group, and at any of the characteristic wavelengths -produced 'by the coincidence of samedirectien, 'comprising a sending sta.

tion{provided'wi-th a single set of antennae, a source of oscillating current, and a series of devices reacting on t-he oscillating current and altering the frequency thereof so as to send each group of signals at different char acteristic wave-lengths; and a receiving station provided with a receiving device adapted to receive equally well at a predetermined series of wave-lengths which are the same as those sent out by the sending station for one group of signals.

5. A system of radiotelegraphy, for transmitting and receiving a plurality of signals at full power at the same time and in the same direction, comprising a` sending station provided with a single set of antennae, a source of oscillating current, and a series of devices reacting on the oscillating current and altering the frequency thereof so as to send signals at different characteristic wave-lengths, and coinciding groups at resultant characteristic wave-lengths distinct from any of the other characteristic wavelengths; and a receiving station provided with means for receiving each group of signals at the characteristic wave-length of that group, and at any of the characteristic wave-lengths produced by the coincidence of groups of signals.

6. A system of-radiotelegraphy, for transmitting and receiving a plurality of signals at full power at the same time and in the same direction, comprising a sending station provided with a single set of antennae, source of oscillating' current, and a series of devices reacting on the oscillating current and altering the frequency thereof so as to send signals at different characteristic wavelengths; and a receiving station provided with a plurality of resonating circuits, each tuned to a predetermined frequency, an amplifying device connected to each resonating circuit, and a translating device common to said resonating circuits and traversed by alternating` current each time the apparatus receives waves of the characteristic wave-lengths.

7.Y A system of ra diotelegraphy, for trans mitting and receiving a plurality of signals at full power at the same time and in the same direction, comprising a sending station provided with a single set of antennae, a source of oscillating current, and a series of devices reacting on the oscillating current and altering the frequency thereof so as to send signals at different characteristic wavelengths, and coinciding groups at resultant lUO characteristic Wave-lengths distinct from any of the other characteristic Wave-lengths; and a receiving station provided With a plurality of resonating circuits, each tuned to a predetermined frequency, an amplifying device connected to each resonating circuit, and a translating device common to said x'esonating` circuits and traversed by alternating current each tiine the apparatus receives Waves of the characteristic Wave 10 lengths.

In testimony whereof I have signed this specication in the presence of two subscribing Witnesses.

HENRI ABRAHAM;

Witnesses:

LON POLART, CHARLES LoN LoIsEL. 

